[dm-devel] dm-verity: Verification fails but do not see Input/Output Error on read
Mikulas Patocka
mpatocka at redhat.com
Thu Aug 8 17:00:56 UTC 2013
On Thu, 8 Aug 2013, Chaitra Bhat wrote:
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> Hi Mikulas,
>
> I get 'Invalid argument' with 'iflag=direct' option when I try to read
> from a verity device using dd.
If you use iflag=direct, block size and offset must be aligned on physical
block size boundary (usually 4k). If they are not aligned, you get invalid
argument error.
> Before I read from the device, I also did 'echo 3 >
> /proc/sys/vm/drop_caches' to make sure caches are dropped.
If the filesystem is mounted, it doesn't drop some buffers (those that are
used by the filesystem). Unmount the filesystem first.
> But as I said before, some locations always fail with I/O error when
> read and others don't.
If you still get misbehavior, even if you bypass the cache with
iflag=direct or with filesystem unmount, create a script that reproduces
it and send it to us.
> Regards,
> Chaitra
Mikulas
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